import { useMemo } from "react";
import { Pressable, Text, View } from "react-native";
import { Plus } from "lucide-react-native";
import * as Haptics from "expo-haptics";
import { REACTION_EMOJIS, type Reactions } from "@/api/types";
import type { Human } from "@/api/types";
import { resolveHumanDisplay } from "@/lib/humans";
import { cn } from "@/lib/utils";

const EMOJI_SET = new Set<string>(REACTION_EMOJIS);

interface ReactionStackProps {
  reactions: Reactions;
  currentHumanId: string;
  humans: Human[] | undefined;
  /** Toggle a reaction (emoji or text) — same contract as ReactionSheet's onToggle. */
  onToggle: (key: string) => void;
  /** Open the full reaction sheet for emoji + custom-text picking. */
  onOpenSheet: () => void;
}

/**
 * Right-edge reaction stack — mobile counterpart of desktop's ReactionBar.
 * Sits vertically centered on the right side of the canvas so the user can
 * see existing reactions at a glance and tap to toggle their own. The "+"
 * affordance opens the ReactionSheet for the full picker (emoji or text).
 */
export function ReactionStack({
  reactions,
  currentHumanId,
  humans,
  onToggle,
  onOpenSheet,
}: ReactionStackProps) {
  const activeEmojis = REACTION_EMOJIS.filter(
    (emoji) => reactions?.[emoji] && (reactions[emoji]?.length ?? 0) > 0,
  );
  const activeTextKeys = useMemo(
    () =>
      Object.keys(reactions ?? {}).filter(
        (k) => !EMOJI_SET.has(k) && (reactions?.[k]?.length ?? 0) > 0,
      ),
    [reactions],
  );

  const handleToggle = (key: string) => {
    void Haptics.selectionAsync();
    onToggle(key);
  };

  return (
    <View className="items-end gap-1.5">
      {activeEmojis.map((emoji) => {
        const reactors = reactions?.[emoji] ?? [];
        const isMine = reactors.includes(currentHumanId);
        return (
          <Pressable
            key={emoji}
            onPress={() => handleToggle(emoji)}
            className={cn(
              "flex-row items-center gap-1 rounded-full px-2 py-1",
              isMine ? "bg-white/25" : "bg-black/45",
            )}
            style={
              isMine
                ? { borderWidth: 1, borderColor: "rgba(255,255,255,0.4)" }
                : undefined
            }
          >
            <Text className="text-sm">{emoji}</Text>
            <Text className="text-white/85 text-xs font-medium">
              {reactors.length}
            </Text>
          </Pressable>
        );
      })}

      {activeTextKeys.map((text) => {
        const reactors = reactions?.[text] ?? [];
        const isMine = reactors.includes(currentHumanId);
        const firstReactor = resolveHumanDisplay(reactors[0], humans);
        return (
          <Pressable
            key={text}
            onPress={() => handleToggle(text)}
            className={cn(
              "flex-row items-center gap-1.5 rounded-full py-1 pl-1 pr-2.5",
              isMine ? "bg-white/25" : "bg-black/45",
            )}
            style={[
              { maxWidth: 200 },
              isMine
                ? { borderWidth: 1, borderColor: "rgba(255,255,255,0.4)" }
                : null,
            ]}
          >
            <View className="bg-white/15 h-5 w-5 items-center justify-center rounded-full">
              <Text className="text-white text-[9px] font-semibold">
                {firstReactor.initials}
              </Text>
            </View>
            <Text
              className="text-white/90 text-xs"
              numberOfLines={1}
            >
              {text}
            </Text>
            {reactors.length > 1 ? (
              <Text className="text-white/60 text-xs">{reactors.length}</Text>
            ) : null}
          </Pressable>
        );
      })}

      <Pressable
        onPress={onOpenSheet}
        accessibilityLabel="Add reaction"
        className="h-8 w-8 items-center justify-center rounded-full bg-black/45"
      >
        <Plus color="rgba(255,255,255,0.85)" size={16} strokeWidth={2} />
      </Pressable>
    </View>
  );
}